1. Field of the Invention
The present invention relates to a bridge having at least one top chord of concrete and a bottom chord of concrete or of metal, said chords being connected to each other by means of structural elements which resist shearing forces.
The two bridge members or chords transmit the moments whilst the structural elements or webs placed between these chords transmit the shearing forces.
2. Description of the Prior Art
In known bridge designs, the webs are constituted by a series of bars arranged in an N-shaped structure. Some of these bars work in compression whilst others work in tension.
The chords and the webs can be of concrete and/or of steel.
In other known designs such as those disclosed, for example, in Swiss patent No. 378,504 and in French patent Application No. 2,494,400, the webs disposed between the chords are constituted by elements of pleated sheet steel. These steel sheets are non-continuous or in other words separated from each other in the direction of the length of the bridge.
In all known designs, should it be desired to obtain webs which are capable of transmitting high shearing forces, it is necessary to increase the number of webs and/or to increase the thickness of these latter. Thus in the case of structures which are intended to sustain very high shearing forces, the construction is heavy and consequently difficult to carry into effect.
The aim of the present invention is to provide a bridge which affords resistance to very high shearing forces while being of lightweight design and easy to construct.